Resinous condensation product.



UNITED STATES PATENT OFFICE.

EDWARD S. DAWSON, JR... OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL'ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

RESINOUS CONDENSATION PRODUCT.

No Drawing.

Specification of Letters Patent.

Application filed' May 31. 1913.

Patented Jan. 2'7, 1914.

Serial No. 770,893.

To all whom it may concern:

Be it knoyvn that I, EDWARD S. Dawson, J12, a. citizen "of the UnitedStates,- residing at Schenectady, county of Schenectady, State of NewYork, have invented certain new and useful Improvements in ResinousCondensation Products, of which the following is a specification.

The present invention comprises a com position suitable as a varnish, orimpregnant for insulating, and other purposes.

\Vhen citric acid combines with a polyhydric alcohol, such as glycerin,it forms a hard, strong resinous material Which may be madesubstantially infusible and insoluble by heating. Although this materialpossesses some degree of tenacity and resiliency especially in thinlayers it does not possess the flexibility desirable for some purposes,for example when used as an impregnant for paper or fabric forelectrical insulating purposes.

In accordance with my invention greater flexibility is imparted to theresin by mixing with the ingredients entering into its constitution anorganic compound of the aromatic series, such, for example, asdinitrobenzene, and then proceeding with. the resinification.

In order to illustrate my invention I will describe in detail. thepreparation of a glycerol resin of citric acid containing aflexibilizing agent. In order to secure complete miscibility of thearomatic substance, I prepare an alcoholic solution of citric acid andglycerin and add to it the flexibilizing agent. For example, to amixture consistin by weight of about 11.4 parts of citric acid, 5 partsof glycerin and 5 parts of methyl alcohol is added about 1 to 10 partsof or even more of any of the following substances,meta-dinitrobenzene,ethyl benzoate, acetanilid, or beta-naphthol or any desired mixture ofthe same. Articles to be impregnated, for example, paper, fabrics, orfabric-insulated electrical coils are dipped into this solution, in somecases repeatedly after intermediate drying. The impregnated articlesvare given first a preliminary baking treatment at a temperature of about125 C. to drive out the alcohol and start the reaction. They are finallyheated to a temperature of about 150 to 200 C. to complete the reaction,the lower temperatures of the range requiring a corresponding longertime. When sheets of paper or fabric are impregnated they may be given asmooth, flat, finish by placing them in a suitable press between metalplates heated to about 150 C. for about 3 to 10 minutes and applying apressure of about 2000 pounds per square inch. They are cooled Whilestill under pressure, and then removed from the press.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is

1. A flexible resinous insulating composition comprising a citrate of apolyhydric a1- cohol and an organic compound of the aromatic series,having insulating properties.

2. A flexible resinous insulating composition comprising a citrate of apolyhydric alcohlol and dinitrobenzene associated therewit 3. Theprocess which consists in dissolving citric acid, a polyhydric alcoholand dinitrobenzene in alcohol and baking to cause chemical reaction withthe formation of a flexible resinous condensation product.

4. The process which consists in dissolving citric acid, glycerin andmeta-dinitrobenzene in alcohol and heating to a temperature of about 125to 200 C. to produce a flexible, insoluble and infusible insulatingmaterial.

In witness whereof, I have hereunto set my hand this 28th day of May1913.

EDXVARD S. DAWSON, JR.

WVitnesses BENJAMIN B. HULL, HELEN ORFORD.

